Counterbalanced stamp mill



April 1939- R. M. GRUSS 2,153,558 7 COUNTERBALANCED STAMP MILL Filed March 9, 1936 2 Sheets-Sheet l INVENTOR.

ATTORNEYS.

A ril 11, 1939. I R SS 2,153,558

COUNTERBALANCED STAMP MILL Filed March 9, 1936 2 Sheets-Sheet 2 INVENTOR. FOL/DVD M GFUJSL W V ATTORNEYS? Patented Apr. 11, 1939 UNITED STATES PATUENT OFFICE 2 Claims.

My invention relates to improvements in counter-balanced stamp mills, and it consists of the combinations, constructions and arrangements hereinafter described and claimed.

In the standard stamp mill the stamps are raised by a cam shaft and then are allowed to drop by gravity. The stamps weigh in the neighborhood of one thousand pounds each, and this necessitates considerable power to raise the stamps.

One of the principal objects of my invention is to provide a stamp mill in which a pair of stamps are connected to a rocker bar in such a manner that one of the stamps is being raised while the other is being lowered, and vice versa. I have found that this construction counterbalances the device so that far less power is necessary to actuate the stamps. It is possible to reciprocate the stamps at a speed of five hundred reciprocations per minute, whereas in the type of stamp mill first mentioned the speed only can be increased to around one hundred and seven blows per minute.

In the old stamp mill a large rock would prevent the stamp from falling the same distance through gravity, and therefore the effective blow of the stamp on the rock also correspondingly lessened. In the present invention the stamps are moved downwardly with the same force re- 00. gardless of the size of the rocks. In order to prevent the device from stalling should a large rock prevent the complete downward movement of the stamp, I provide novel air cushions at each end of each stamp, these air cushions automatically coming into play when the stamp meets a resistance above a predetermined amount. The air cushions at each end of each stamp are sealed by a liquid such as oil, and I provide means for adding oil and air as needed. I also provided means for changing the stroke of the stamps.

Other objects and advantages will appeard in the following specification, and the novel features of the device will be particularly pointed out in the appended claims.

My invention is illustrated in the accompanying drawings forming a part of this application, in which Figure 1 is a vertical section through the device, portions being shown in elevation;

Figure 2 is a section along the line 2-2 of Figure 1;

Figure 3 is a side elevation of the adjustable eccentric taken substantially along the line 33 of Figure 1; and

Figure 4 is a section along the line 4--4 of Figure 1, portions being shown in elevation.

In carrying out my invention I provide a stamp mill comprising two battery posts I connected at their tops by a cross piece 2. Guides 3 and i extend between the battery posts as clearly shown in Figure 1. Mortar blocks 5 and 6 are disposed at the bottom of the device and carry mortars l and 8. These mortars are preferably made of iron and are cup-shaped. Figure 4 shows the mortar 8 as being provided with an inlet opening 9 for receiving the ore to be crushed and the mortar is also provided with'an outlet opening Ill. The opening I0 is covered by a screen i I, and this permits material of only a predetermined size to pass through the opening. The material is delivered onto an amalgamating member indicated generally at 12.

I provide two stamps l3 and I4, and these stamps reciprocate in openings l5 provided in the guides 3 and i. The lower ends of the stamps are received in the mortars l and 8. Since both stamps are identical in construction a description of the stamp M will suffice, and corresponding reference numerals will be given to similar parts in the stamp l3.

The stamp I4 is in the form of a cylinder with a closed bottom IS. A boss head I! is secured to the stamp bottom l6 by and suitable fastening means, such as a cap screw l8. A shoe I9 is removably secured to the boss head ll by means of screws 20 or other suitable fastening means. If desired the shoe l9 may be provided with a projection 2i receivable in a recess 22 in the under side of the boss head IT. The shoe i9 is designed to strike against a die 23. This die is placed in the bottom of the mortar 8, see Figure 4.

I provide means for reciprocating the stamp l4 in the guides 2 and 4. A plunger 24 in the form of a piston is slidably mounted in the cylindrical stamp I4. This plunger has a closed top 25 and the bottom 26 of the plunger is provided with openings 21. A cup washer 28 is secured to the bottom 26 by a disc 29 and a bolt 30. The openings 27 are preferably drilled into the bottom 26 after the cup Washer 28 and the disc or look washer 29 are secured in place. The openings 21 will then extend through the bottom 26 and also through the cup washer 28 and the disc 29.

I fill the bottom of the stamp M with a liquid such as oil 3|, and this oil passes up through the openings 21 and into the interior of the plunger 24 so that the oil level will at all times be disposed above the plunger bottom 26 irrespective of the position of the plunger within the stamp. The oil 3| traps air within a compartment A formed by the interior of the plunger 24 and the oil level 3|. I provide means for adding air under pressure to the compartment A, and this means consists of a valve indicated generally at 32. This valve may be of the Schrader type, and is disposed in the stamp M at a position below the plunger 24. The valve 32 closes the small opening 33 that leads directly into the interior of the stamp l4. When it is desired to add air under pressure to the compartment A an 'air hose, not shown, may be applied to the valve 32, and air will then pass from the hose through the valve into the interior of the stamp M. This air will bubble up through the oil 3| and finds its way into the compartment A. The pressure of the air in the compartment may be of any pressure desired, such as for example, fifty pounds.

When it is desired to add oil to the interior of the stamp l4 the valve insides may be removed and then oil forced through the valve casing and into the interior of the stamp, after which the valve insides may be reinserted. It will be seen from this construction that I provide an oil seal for the air compartment A. The purpose of the air compartment A will be hereinafter set forth.

At the top 25 of the plunger 24 I provide a second cup washer 34. This cup washer is held in place by a disc 35 that is mounted on a reduced portion 36 of a piston rod 31. The piston rod is connected to the plunger by means of a nut 38. The rod 31 is slidably received in a sleeve 39 that is integral with and depends from a head 40. The head 40 is screwed into the open top of the stamp M. A stuffing gland 4| seals the piston rod.

I provide an air valve 42 in the head 40 and through this valve I can force either air or oil. The valve 42 controls an inlet opening 43 in the head 4|]. Oil is forced through the inlet 43 and fills the interior of the stamp l4 from a position adjacent to the cup washer 34 and upward. Sufi'icient oil is added to cause the oil level 44 to rise above the bottom of the sleeve 39. This oil traps air in a compartment B formed by the cylindrical wall of the stamp M, the head 4|], and the oil level 44. After the oil has been added through the inlet 43 air is forced through the valve 42 and this air under pressure will fill the compartment B to the desired pressure which is approximately fifty pounds. The purpose of the air compartment B will be described hereinafter.

The piston rod 31 is slidably mounted in a bearing 45 and this bearing is carried by the cross piece 2. The upper end of the piston rod 31 is connected to a rocker bar 46 by means of a toggle 41 or other suitable fastening means. A fulcrum support 48 is carried by the cross piece 2 and the rocker bar 46 is fulcrumed to this support at 49. In like manner the piston rod 31 associated with the stamp I3 is connected to the rocker bar 46 by a toggle joint 41. It will be seen from this construction that the weight of one stamp which is approximately one thousand pounds balances the weight of the other stamp because as one stamp is moved downwardly the other stamp is moved upwardly by the rocker bar 46.

I provide an eccentric means for actuating the rocker bar 46 and this means is shown in Figures 1 and 3. A link 50 is connected to the free end of the rocker bar ,46 at 5|, and the other end of the link is connected to a pin 52. Figure 3 shows the pin 52 being carried by an adjustable member 53, securable to an eccentric 54. The eccentric 54 has a plurality of transverse grooves 55 therein, and the member 53 has a corresponding number of transverse projections 56. The projections 56 and grooves 55 are such that the member 53 may be adjusted with respect to the eccentric 54, and thus the pin 52 can be disposed nearer or further away from a drive shaft 51. Cap screws 58 or other suitable fastening means may be used for securing the member 53 to the eccentric 54. Figure 1 shows the drive shaft 51 supported by a bracket 58 and this in turn is connected to the battery post From the foregoing description of the various parts of the device, the operation thereof may be readily understood.

The member 53 is adjusted with respect to the eccentric 54, and this determines the length of the stroke of the stamps l3 and M. The stamps are reciprocated by the rocker bar 46 and are positively moved downwardly and upwardly. Inasmuch as one stamp is being moved downwardly while the other one is being moved upwardly the weight of the stamps will balance each other and this reduces the power necessary to operate the device. Moreover the balancing of the two stamps permits the device to be operated at a higher speed than is possible where the stamps are lifted by cams and then are allowed to drop by gravity.

The ore is fed through the opening 9 and builds up on the die 23. Water is mixed with the ore. The ore is crushed between the shoe I9 and the die 23 and when this ore reaches a predetermined fineness it will pass out through the opening I0 and the screen II. In this way the device is continuous in operation.

Although I provide a positive action for operating the stamps I make use of the double acting air spring for each stamp, and this air spring comes into play automatically when a stamp strikes ore and is prevented from moving through its entire stroke. The double air spring referred to consists of the air compartments A and B where the air is trapped by means of the two bodies of oil.

For example, when the stamp l4 in Figure 1 is moved downwardly by the rocker bar, the shoe l9 will strike the ore on the die 23 with sufiicient force to crush the ore. Normally the stamp M will take a complete stroke but should the ore prevent this complete stroke the rocker bar 46 will move the plunger 24- downwardly in the fluid 3|, and the air within the compartment A will be compressed. The air in the compartment is already under approximately fifty pounds pressure, and therefore the stamp M will deliver a blow on the ore strong enough to break it even though the stamp should be prevented from completing its entire stroke. The plunger 24 will move through its complete stroke and the compartment A will automatically take up any difference of movement betweenthe plunger and the stamp M.

The cup leather 28 prevents the oil 3| from passing around the plunger 24 and finding its way to the compartment B. The rocker arm 46 in lifting the stamp I4 first moves the plunger 24 upwardly. This movement compresses the air within the compartment B until the pressure is sufficient to lift the stamp |4. Further upward movement of the plunger 24 will now lift the stamp therewith.

It will be noted from Figure 1 that the air in the compartment B is trapped from flowing along the rod 31 inasmuch as the rod slides in the sleeve 39 and this sleeve at all times has its lower end immersed in the oil. The oil itself is prevented from passing along the rod 31 by the stuffing gland 4!. The cup leather 34 prevents the oil from passing downwardly along the sides of the plunger 24.

It will be seen that the double acting air spring provides a floating plunger 24 which acts between two air pressures confined in the compartments A and B. The air in the two compartments is sealed by the oil. I have found that the momentum of the reciprocating stamps l3 and M will aid in providing a uniform operation of the device in much the same manner as a fly wheel is used for providing a uniform operation to the crank shaft of an internal combustion engine. The device is simple in construction, and is durabe] and eflicient for the purpose intended. Should any oil leak past the cup leather 28 on the down stroke of the stamp, this will be offset by the oil in the compartment B tending to be forced past the cup leather 34 during the up stroke of the stamp.

While I have shown only the preferred form of my invention, it should be understood that various changes or modifications. may be made within the scope of the appended claims without departing from the spirit of the invention.

I claim:

1, In astamp mill, a stamp comprising a cylmeter, a hollow piston slidable in the cylinder, the bottom of the piston being perforated, the bottom of the cylinder and the bottom of the piston receiving a fluid that traps a body of air in the top of the piston, a cover closing the top of the cylinder and having an integral sleeve extending down into the cylinder, a piston rod for the piston and being slidably received in the sleeve, the portion of the cylinder immediately above the piston top receiving a fluid that immerses the inner end of the sleeve and traps a second body of air in the top of the cylinder, and means for reciprocating the piston rod for reciprocating the stamp.

2. In a stamp mill, a stamp comprising a cylinder, a hollow piston slidable in the cylinder, the bottom of the piston being perforated, the bottom of the cylinder and the bottom of the piston receiving a fluid that traps a body of air in the top of the piston, a cover closing the top of the cylinder and having an integral sleeve extending down into the cylinder, a piston rod for the piston and being slidably received in the sleeve, the portion of the cylinder immediately above the piston top receiving a fluid that immerses the inner end of the sleeve and traps a second body of air in the top of the cylinder, and means for reciprocating the piston rod: for reciprocating the stamp, and. means carried by the lower portion of the cylinder and the cover for adding additional air to the two bodies of air as needed.

ROLAND M. GRUS S, 

